JPH1178406A - Traveling body with lug - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent mud adhesion and heighten separation resistance from a tread layer by covering the surface of a tread with a mud adhesion preventive layer formed of two or more elastic body layers with low hardness, and arranging elastic bodies with lower hardness toward an outermost layer. SOLUTION: A tire 1 is provided with a plurality of lugs 3 arranged with spaces in the circumferential direction of a tread 2, and the surface of the tread including the side faces of the lugs 3, a side wall part 4 and a shoulder area 5 is covered with a mud adhesion preventive layer 6 formed of two elastic body layers with low hardness. The mud adhesion preventive layer 6 consists of an outermost layer 6A and an intermediate layer 6B. The outermost layer 6A is formed of a foam rubber layer of mixed closed cells of natural rubber and polybutadiene rubber with a thickness of 1-2 mm, an average foaming diameter of 100-300 μm, an ASKAR-C hardness of 20-40 and specific gravity of 0.5, and the intermediate layer 6B is formed of a foam rubber layer of mixed closed cells of natural rubber and polybutadiene rubber with a thickness of 1-2 mm, an average foaming diameter of 100-300 μm, an ASKAR-C hardness of 40-60 and specific gravity of 0.8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rugged traveling body, and more particularly to a rugged traveling body for a vehicle which prevents harmful effects due to adhesion of mud when traveling in a muddy area or a wetland area.

[0002]

2. Description of the Related Art In recent years, the situation of land and housing development is that agricultural land is often converted to residential land and developed.
As a result, there are many areas where agricultural land and residential land are mixed. In such areas, farm roads and the like are often used as general roads, and the roads are often paved, so tractors that have completed work on wetlands, soft lands, or mud lands that are cultivated lands. Alternatively, an agricultural vehicle such as a rice transplanter travels on the general pavement road, and when it travels, mud or the like adhering to a vehicle with lugs such as tires or crawlers of the vehicle is scattered on the road. It was scattered and caused problems that could cause pollution.

[0003] In some cases, after the work on one agricultural land is completed, the agricultural vehicle continues to work on another agricultural land. In such a case, the one agricultural land may be used. The mud or the field soil is moved to another agricultural land while the mud or the field soil remains attached to the traveling body, and thereafter, the mud or the field soil is dropped on the agricultural land. If the mud or upland soil of the one arable land is contaminated with the pathogen of the crop cultivated there, the mud or upland soil of the other arable land is also contaminated with the pathogen, and the pathogenic bacteria pass through the healthy arable land. There was a problem that the agricultural land would become widespread and the crops grown there would be damaged.

Conventionally, as means for preventing adhesion of mud or the like on a rugged traveling body of this type of agricultural vehicle, a large number of lags arranged on a tread of the traveling body are reduced to reduce the number of lags between the lugs. It is known that traction is exhibited when the traveling body travels on the ground by increasing the groove width. However, the extreme decrease in the lag significantly reduces the traction, so that the lag cannot be reduced enough to obtain a sufficient mud adhesion preventing effect.

As another conventional means for preventing adhesion of mud or the like on a traveling body with lugs, a thin rectangular mud fin is arranged at the groove bottom between the lugs so as to slightly project from the lug bottom in parallel with the lugs. There has been proposed a technology (see Japanese Utility Model Laid-Open No. 60-118502) in which the mud sweeping property is improved by doing so. The proposed technology is intended to prevent a decrease in traction due to mud clogging between the rugs, and has a certain degree of mud adhesion preventing effect, but in a soft zone where the sinking depth of the rugged traveling body becomes large, In the wetland mud in the wetland field, the mud fin movement was not effective for mud sweeping, and the mud was more likely to be clogged.

Further, in order to increase the movement of the lug bottom and to prevent adhesion of other mud or the like, means for providing a groove in the lug bottom (Japanese Utility Model Laid-Open No. 6-32110) or the thickness of the lug bottom is reduced. Means for reducing the thickness (see Japanese Utility Model Publication No. 61-23448) and the like have been proposed, but none of them can provide sufficient movement of the lag bottom to drop the mud, and the mud adhesion prevention effect is not sufficient.

Therefore, the applicant of the present application has previously filed Japanese Patent Application No.
As an invention of the application of Japanese Patent Application No. 0074 (see Japanese Patent Application Laid-Open No. 8-324209), in a traveling body with a lug having a plurality of lugs arranged on a tread at intervals in a circumferential direction, the surface of the tread is lowered. A technique of coating with a mud prevention layer comprising an elastic layer of hardness has been proposed.

As shown in FIG. 5, the proposed traveling body with lugs includes a traveling body with lugs 1 'provided with a plurality of lugs 3 arranged on a tread 2 at intervals in a circumferential direction.
Back and sides, lug bottom 8 and sidewall 4
The surface of the tread 2 including the shoulder region 5 is covered with a mud adhesion preventing layer 6 made of a low-hardness elastic layer, and a carcass 7 and a beat core 9 are disposed inside the tread 2.

The mud adhesion preventing layer 6 effectively promotes the separation of the adhering mud due to its soft elastic deformation action. In the production of the traveling body 1 'with lugs, the mud adhesion preventing layer 6 is used. A tread member in which the layer 6 and the tread 2 are integrally laminated is joined to a base of the traveling body to form a molded unvulcanized traveling body, a so-called flat green tire. The tread rubber member 2 in which a tire formed into a tire shape at the time of use, that is, one sheet of a low-hardness elastic layer 6 is adhered to the tread surface before vulcanization, or the low-hardness elastic layer is used. An extruded tread rubber member 6 provided on the surface layer 6 is used.

[0010]

By the way, the mud adhesion preventing layer 6 made of one low-hardness elastic body peels off the mud adhering to the groove between the lugs 3 and 3 by its soft elastic deformation action. However, when the hardness of the mud adhesion preventing layer 6 is low, that is, when the elastic deformation is large, the mud adhesion preventing layer 6 remains crushed by the weight of the mud and impairs the mud adhesion preventing function due to the elastic deformation. However, there arises a problem that the settling occurs and the durability becomes poor. Further, there is a problem that when the hardness of the mud adhesion preventing layer 6 is increased, necessary elastic deformation is not caused, and the original mud soil adhesion preventing function is not generated.

Further, when traveling in a field, the mud adhesion preventing layer 6 receives compressive shear stress and strain due to mud on the boundary surface with the tread 2 having high hardness. When the hardness difference between the mud adhesion preventing layer 6 and the tread 2 is large, the degree of concentration of compressive shear stress and strain at the interface becomes particularly large, and the mud adhesion preventing layer 6 And the tread 2 tend to peel or break. For this reason, the one layer of the mud adhesion preventing layer 6 may have a problem that the peeling durability between the layers is reduced and the effect of preventing the mud adhesion is not continuously expected.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a method for driving a work such as mud or the like even when the agricultural land is a wetland, a soft land, or a muddy land. It is an object of the present invention to provide a traveling body with lugs, which comprises a mud adhesion preventing layer which is difficult to adhere to, and which has an enhanced durability of separation of the mud adhesion preventing layer from a tread layer.

[0013]

SUMMARY OF THE INVENTION In order to achieve the above object, a lug traveling body of the present invention includes a plurality of lugs circumferentially spaced on a tread, and includes at least side surfaces of the lugs. It is characterized in that the surface of the tread is covered with a mud adhesion preventing layer composed of two or more layers of low-hardness elastic bodies, and the lower-layer elastic bodies are disposed closer to the outer layer elastic bodies.

In the traveling body with lugs of the present invention, at least the surface of the tread including the side surfaces of the lugs is covered with a mud adhesion preventing layer made of a low-hardness two-layer elastic body.
When the vehicle travels in a wetland or the like, the peeling of the mud can be effectively promoted by the flexible elastic deformation of the two-layer mud adhesion preventing layer without reducing the required driving force.

Further, the mud adhesion preventing layer is a multilayer elastic body having two or more layers having lower hardness as the outer layer, so that the boundary between the mud adhesion layer received from the mud and the tread during traveling in the field. The compressive shear stress and strain on the surface are reduced at each boundary surface of the multilayer, preventing concentration and dispersing, between the mud adhesion layer and the tread portion, or
The peeling between the elastic layers can be reduced, and the peeling durability can be improved.

Further, the number of layers of the mud adhesion preventing layer is not limited to two, but may be three or more as long as the two functions can be simultaneously performed. The part to be installed is the side of the lug, the side wall part, and
The entire surface of the tread including the shoulder region may be covered, for example, only the lug bottom where the concentration of compressive shear stress and strain is relatively large, or only the local portion including the lug front surface. You may do so.

In a specific embodiment of the mud adhesion preventing layer of the traveling body with lugs according to the present invention, the outermost elastic body is made of ASK.
It has an AR-C hardness of 2 to 70, a foamed rubber layer of closed cells having a specific gravity of 0.02 to 0.8, and the other intermediate layer elastic body has an ASKAR-C hardness of 20 to 75 and a specific gravity of 0.1 to 0.1.
It is characterized by comprising a foamed rubber layer of 1.0 closed cells.

When the hardness of the outermost layer elastic body becomes less than the above value, the elastic body remains crushed by the weight of the mud, thereby impairing the mud adhesion preventing function due to elastic deformation and causing settling. If the hardness becomes more than the above value, the outermost layer elastic body will be in a hard state that does not cause elastic deformation necessary for peeling mud, so that the mud adhesion preventing function It is necessary to set the hardness within the above-mentioned range, since the hardness is not obtained.

If the specific gravity of the outermost elastic body is less than the above value or more than the above value, the mud adhesion preventing function is impaired for the same reason as the hardness. Accordingly, the hardness and specific gravity of the outermost layer elastic body are ASK
It is necessary that the AR-C hardness is in the range of 2 to 70 and the specific gravity is in the range of 0.02 to 0.8, but from the above properties, the hardness is preferably 3 to 50 (more preferably 5 to 30), and the specific gravity is 0. It is better to be in the range of 0.05 to 0.6.

Further, if the hardness of the intermediate layer elastic body is higher than the above value, the hardness difference between the outermost layer elastic body and the intermediate elastic body becomes large, and the buffer function of the interface between the two layers becomes low. As a result, the durability function is reduced. On the other hand, if the intermediate layer elastic body has a hardness equal to or less than the above value, the buffer function at the interface between the intermediate elastic body and the tread rubber layer is reduced, and the durability function is similarly reduced. Therefore, the hardness needs to be within the above range.

When the specific gravity of the intermediate layer elastic body is not more than the above value or not less than the above value, the buffer function of the interface between the layers is lowered for the same reason as the hardness, and the durability function is reduced. I will.

Therefore, the hardness and specific gravity of the intermediate layer elastic body are ASKAR-C hardness 20 to 75 and specific gravity 0.1 to 0.1.
It is necessary to be within the range of 1.0, but from the above properties, preferably the hardness is 30 to 60 and the specific gravity is 0.3 to
It is better to be in the range of 0.8.

Further, since the foamed rubber, which is the material of the outermost layer elastic body and the intermediate layer elastic body, exerts an elastic deformation action, a closed cell having excellent durability is preferable. In addition, since the open-cell body is inferior in durability to the closed-cell body in structure, it is not suitable as a mud adhesion preventing layer.

Further, as another specific embodiment of the mud adhesion preventing layer of the traveling body with lugs according to the present invention, the thickness of the outermost elastic body is 1 to 2 mm, and the thickness of the intermediate elastic body is The thickness is 1 mm.

By setting the thickness of the outermost layer elastic body and the intermediate layer elastic body within the above-mentioned range, and setting the hardness and specific gravity within the above-mentioned range, the mud adhesion preventing function and the durability function are achieved. Can be realized effectively. However, the thickness of the elastic body is selected depending on the number of layers of the elastic body, the hardness, and the like, and is not limited to the above value.

[0026]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a vehicle equipped with a lug according to the present invention. FIG. 1 and FIG. 2 show a bias tire 1 (hereinafter simply referred to as a tire) which is a traveling body with lugs according to an embodiment of the present invention. The tire 1 is for an agricultural work vehicle (tractor) having a tire size of 11.2 to 24, and includes a plurality of lugs 3 arranged at intervals in an outer peripheral direction of the tread 2, and a side surface of the lug 3, The surface of the tread including the side wall portion 4 and the shoulder region 5 is entirely covered with a mud adhesion preventing layer 6 composed of two layers of a low-hardness elastic body. In the tread 2, a carcass 7 and a beat core 9 are arranged. As shown in FIG. 2, the mud adhesion preventing layer 6 may cover the top 3A of the lug 3 or may not cover the top 3A.

As shown in cross section in FIG.
The low hardness two-layer elastic mud adhesion preventing layer 6 includes an outermost layer 6A and an intermediate layer 6B, and the two layers 6A and 6B are laminated on the tread 2 with a substantially uniform thickness. The outermost layer 6A has a thickness P1 of ₁ to 2 mm and an average foam diameter of 100 to 3 mm.
00 μm, ASKAR-C altitude 20-40, specific gravity 0.5
The foamed rubber layer is a mixture of closed cells of natural rubber and polybutadiene rubber. The intermediate layer has a thickness P ₂ of 1 mm, an average foam diameter of 100 to 300 μm, and an ASKAR-C altitude of 40 to 6
It has a foamed rubber layer of a mixed closed cell of natural rubber having a specific gravity of 0.8 and polybutadiene rubber.

FIG. 4 is a cross-sectional view of the tire 1 of the present embodiment before vulcanization, and foaming of a closed system closed cell of the natural rubber and polybutadiene rubber in two layers 6A and 6B of low hardness on the tread 2. A mud adhesion preventing layer 6 made of a rubber layer is integrally laminated by sticking a sheet.

The rubber composition of the foamed rubber layer of the outermost layer 6A in this embodiment is shown in Table 1, and the rubber composition of the foamed rubber layer of the intermediate layer 6B is shown in Table 2.

[0030]

[Table 1]

[0031]

[Table 2]

In the outermost layer 6A and the intermediate layer 6B of this embodiment, a foamed rubber layer of a mixed closed cell of natural rubber and polybutadiene rubber is used. However, styrene butadiene rubber (SBR), isoprene rubber ( IR), a diene rubber such as polybutadiene rubber (BR), acrylonitrile butadiene rubber (NBR) or ethylene polypropylene diene rubber (EPDM), or a closed-cell foamed rubber layer such as urethane rubber can also be used.
Also, instead of the closed-cell foamed rubber layer, ASKAR-C
A mud adhesion preventing layer composed of a soft non-foamed rubber layer containing a high oil such as polynorbornene, diene rubber or urethane rubber having a hardness of 2 to 75 can be used.

[Test Example] In order to test the tire of the above embodiment of the present invention, the tire of the comparative example was the same as the tire of this embodiment except that the elastic body had only one outermost layer. A tire coated with a mud adhesion preventing layer composed of an elastic layer was molded and vulcanized under the same conditions as in the tire of the present example.

A comparative test was performed on the tire of this example and the tire of the comparative example. The test conditions were as follows.
Assemble × 24 rim and fill with 1.2Kg / cm ² internal pressure,
Attached to the rear wheel of a four-wheel drive 25 ps tractor, after rotating the wet paddy for one round, weighing the amount of mud adhering to the tire surface, and then traveling 30 m on the ridge, The amount of mud dropped on the road from the tires when traveling on the paved road was weighed.

As a result of the test, the tire of this example showed a higher effect of reducing the amount of mud adhering and falling than the tire of the comparative example, and peeling of the boundary surface between the elastic layer and the tread rubber layer. The durability was improved, and the life durability was increased by 30% compared to the comparative example.

As described above, one embodiment of the present invention, that is, a specific example of the traveling body with a lug (tire) has been described in detail. However, the present invention is not limited to the traveling body with a lug of the above embodiment. However, various modifications can be made without departing from the spirit of the invention described in the claims.

For example, in the above embodiment, the two layers of the mud adhesion preventing layer are used. However, the present invention is not limited to the two layers.
The number of layers is not limited to two, but may be three or more. Further, in the above embodiment, the thickness of the outermost layer is 1 to 2 mm and the thickness of the intermediate layer is 1 mm, but the thickness of the two-layered elastic body depends on the number of layers and hardness of the elastic body. It is changed by being changed, and is not limited to the above value.

In the above embodiment, two unvulcanized foamed rubber layers are stuck on the tread before vulcanization as a manufacturing method.
Although a vulcanized product is used, a foam sheet molded separately in a predetermined manner on the tread surface of the tire after vulcanization may be attached in two layers at a time as the mud adhesion preventing layer, You may stick it individually by one layer. Alternatively, a production method by spraying may be used.

[0039]

As will be understood from the above description, the running body with lugs of the present invention is characterized in that the surface of the tread including at least the side surfaces of the lugs is provided with a mud adhesion preventing layer comprising two or more layers of low-hardness elastic bodies. By doing so, it is possible to prevent the adhesion of mud without substantially reducing the driving force required when traveling on wetlands, soft ground, or muddy land, etc., and to take out mud when leaving the wetland etc. It can be minimized, and when traveling on a paved road or the like, it is possible to reduce the contamination of the road or the spread of pathogenic contamination of farmland.

Further, when traveling in a field, the compressive shear stress and strain at the interface between the mud adhesion layer and the tread portion, which are received from the mud, are alleviated at each of the multilayer interfaces to prevent concentration. By dispersing, the separation between the mud adhesion layer and the tread portion or between the elastic layers can be reduced, and the peeling durability can be improved.

[Brief description of the drawings]

FIG. 1 is a partial plan view of a tread of a tire (running body with lugs) according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the tire shown in FIG.

FIG. 3 is a sectional view of the tire shown in FIG.

FIG. 4 is a sectional view showing a green tire (molded unvulcanized) of the tire of FIG. 1;

FIG. 5 is a cross-sectional view of a prior art tire.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Running body with a lug (tire) 2 Tread 3 Lug 3A Top of lug 4 Side wall part 5 Shoulder part 6 Mud adhesion prevention layer 6A Outermost layer 6B Middle layer 7 Carcass 8 Lug bottom 9 Beat core

Claims (5)

[Claims] 1. A traveling body with lugs having a plurality of lugs arranged at intervals in a circumferential direction on a tread, wherein the surface of the tread including at least side surfaces of the lugs is made of a low-hardness elastic body having two or more layers. A traveling body with lugs, which is covered with a mud adhesion preventing layer. 2. The running body with lugs according to claim 1, wherein the mud adhesion preventing layer is provided with an elastic body having a lower hardness as the outer layer elastic body. 3. The foamed rubber layer having closed cells having an ASKAR-C hardness of 2 to 70 and a specific gravity of 0.02 to 0.8, wherein the outermost elastic body is formed. A traveling body with lugs. 4. The intermediate layer elastic body according to claim 1, wherein the intermediate layer elastic body comprises a closed-cell foamed rubber layer having an ASKAR-C hardness of 20 to 75 and a specific gravity of 0.1 to 1.0. A traveling body with a lug according to any one of the preceding claims. 5. The thickness of the outermost elastic body is 1 to 2 mm.
5. The traveling body with lugs according to claim 1, wherein the thickness of the intermediate layer elastic body is 1 mm. 6.